[lifo]

Cramp is a fully asynchronous web framework that's very good at dealing with thousands of open connections. It supports WebSockets (latest protocol) and Server-sent Events out of the box. Optionally, supports using Ruby 1.9 fibers to prevent spaghetti evented code - which means seamless Active Record integration.

[boundlessdreamz]

How does it compare to node.js? When is cramp a good fit compared to node.js and vice versa?

[lifo]

It's a great fit when you need to use your existing Ruby code. Active Record models for example. It works very good alongside async sinatra as well.

All said, it all boils down to your personal choice of languages.